Radiography

Question 1

Frequency vs Wavelength

Answer 1

Inversely Proportional
* greater frequency = shorter wavelength

Question 2

RAD

Answer 2

Measures energy transferred by radiation to body part
* absorbed dose
* unit is gray (Gy) = 100 rad

Question 3

REM

Answer 3

Dose equivalent
* how radiation affects each tissue
* unit is Sievert (Sv) = 100 rem

Question 4

Radiation Safety
3 Rules

Answer 4

• Time
• Distance
• Shielding

Question 5

kV

Answer 5

Controlled by autotransformer
* increases voltage to produce x-rays
* controls acceleration of electrons
* only adjust according to tissue size (penetrating ability)
* increased = low contrast (more shades)

Question 6

mA and mAs

Answer 6

• mA = controls current
• mAs = controls blackening / density of image
• Use to fine-tune image = minimize motion by setting this high with short time
• Increased = darker image

Question 7

Cathode

Answer 7

• Negative charge
• Source of electrons
• Thicker part of animal should be closer to here

Question 8

Anode

Answer 8

• Positive charge

Question 9

Focal Spot

Answer 9

• Found on the anode side
• Area where electrons are attracted
• Smaller focal spot = sharper image but heat more concentrated

Question 10

Grid

Answer 10

• Used when area is thicker
• Prevents scatter radiation from reaching film
• Absorbs part of primary beam - need to have higher mAs or kV

Question 11

Tissue Density
Low to High

Answer 11

• Gas
• Fat
• Water
• Organs
• Muscle
• Bone
• Metal

Question 12

Film Processing Steps

Answer 12

• Developing
• Rinsing / Stop bath
• Fixing
• Washing
• Drying

Question 13

Developer

Answer 13

Reduces / converts exposed silver crystals to black
* more converted crystals = darker image
* unconverted crystals get washed away by fixer

Question 14

Rinse

Answer 14

Stops the developing process

Question 15

Fixer

Answer 15

Removes unexposed / not converted crystals from film
* hardens film to make it permanent

Question 16

Washing

Answer 16

Removes processing chemicals from film
* prevents film discoloration / fading over time

Question 17

Contrast

Answer 17

Various shades of black, gray, and white
* high = black and white (best for bone)
* low = more variations in between (best for soft tissue)

Question 18

Radiopaque

Answer 18

• Positive contrast
• Appears white on images
• Soluble: absorbed into blood, excreted by kidneys; iodine
• Insolube: goes through GI tract; barium

Question 19

Radiolucent

Answer 19

• Negative contrast
• Appears black on image - no x-rays absorbed
• Ex: air, CO2, and NO2